Two Hamilton families had to evacuate their homes early Monday morning because of a gas leak in the neighborhood.

The leak was first reported at 11:30 p.m. on Sunday at 50 Mill St., according to Hamilton Fire Chief Phil Stevens Jr. and National Grid spokesman David Graves.

While 50 Mill St. was checked by firefighters and found to not have any gas inside the home, nearby at 54 Mill St. there were “strong readings” of gas.

“The residents were not aware of the leak and were evacuated,” Stevens said.

After that, 52 Mill St. was also evacuated.

In all, firefighters checked the gas level in nearly a dozen homes on Cottage and Mill streets. Elevated levels were found at 52 Mill St. and 54 Mill St. and the residents were told to leave the home but the readings were zero in the other homes.

A National Grid crew arrived at about 12:30 a.m. and began repairs, Graves said. The leak occurred in the service line that runs for the main line under the street to the home, Graves said.

It wasn’t know what caused the leak, he said.

The leak was repaired by 3:45 a.m. and the displaced residents could have returned to their homes but didn’t, Stevens said.

National Grid crews stuck around until 6 a.m. when the residents returned to relight the pilot lights, Graves said.

Nobody at either of the evacuated homes could be reached for immediate comment on Monday morning.